Update contributing md

CONTRIBUTING.md

@@ -1,6 +1,14 @@
 # Contribution Guidelines
 
 Please ensure your pull request adheres to the following guidelines:
-- If book is english edition, use the following format: `*BOOK NAME* by author [amazon.com](LINK)`.
+
+- Search previous suggestions before making a new one, as yours may be a duplicate.
+- Make an individual pull request for each suggestion.
+- Use the following format: `*BOOK NAME* by author [Edition](LINK)`.
+- Link to the Amazon.com url.
+- New categories, or improvements to the existing categorization are welcome.
 - Check your spelling and grammar.
-- Remove any trailing whitespace.
+- Make sure your text editor is set to remove trailing whitespace.
+- The pull request should have a useful title and include a link to the package and why it should be included.
+
+Thank you for your suggestions!